Project Scope

Sq. Footage:

Levels/Floors:

Structural Precast Elements:

Award:

2006 PCI Harry H. Edwards Design Award

Designers created an all-precast concrete structural system that emulated cast-in-place construction to meet the owner’s needs, which included the restriction of having 21-inch total depths for floor joists and 28-inch total depths for beam lines. To achieve this, the precaster created two new product lines.

The first product consisted of “tri-slab” deck members that were 12 feet wide by 18 inches deep. The members feature three stems, a half-stem on each end and a full stem in the middle. This allowed the two half-stems to create a full stem when they were placed side by side, creating a joist that was 6 feet on center. The sides of the tri-slabs have a shear key running the full length of the half stems, so they can be grouted together to eliminate welded connections.

The second product line was a W-shaped beam that was 36 inches wide by 25 inches deep. The W-shaped cross-section comprises a center web and two thinner outside webs that each have pocket blockouts into which the tri-slab stems fit. After the tri-slabs were set, two trough sections were formed on either side of the center web of the W-beam. These troughs were poured in the field to lock them together. The W-beams threaded over rebar couplers on the columns, and the connections were grouted together. Each floor then received 3 inches of field topping to complete the system.

The architectural precast concrete cladding panels serve as intermediate moment frames for lateral-load resistance in the long direction of the building. The result of these design innovations was to give the owner the continuity available with cast-in-place concrete while providing the speed, quality, convenience and cost of a precast concrete design.

DESIGN CHALLENGE: Create a seven-story, 210,000-square-foot Class A office building with restaurant and retail space on the ground floor. The building must feature continuous-span construction for beams and floor joists, as well as no welded connections, to avoid increased maintenance costs.